(a) Field of the Invention
The present invention relates to a lampshade for LED and more particularly to a LED lampshade injection-molded or pressure cast with an IMD (In-Mold Decoration) film, which allows quick dissipation of heat from the LED, and can be used with a blue LED to produce white and light of different colors.
(b) Description of the Prior Art
An IMD film is for decorating a device during the molding or pressure casting cycle. Many plastic components, such as shells for cell phones, cosmetics cases, key pads, automobile parts, information and electric component parts, etc. need a special surface finish to appear in high quality. IMD is one of the most efficient and cost-effective choices for that purpose. In-Mold Decoration (IMD) can provide several important advantages over other decoration methods.
Further, during the fabrication of LEDs (light emitting diodes), silicon rubber containing a fluorescent substance is applied to LED chips by a resin dispenser and then encapsulated with a packaging resin. The silicon rubber may contain yellow, red, or green fluorescent substance for changing the color of the light of the LED chip, for example, for producing white light. However, this resin dispensing procedure is not suitable for mass production.
The aforesaid conventional method is to embed LED chip in the silicon rubber. Because the silicon rubber fills up the gap in the LED lamp around the LED chip, heat cannot be quickly dissipated from the LED chip during the operation of the LED lamp. Under the effect of heat, the silicon rubber cracks easily, and the lead wires of the LED chip may break. Therefore, regular LEDs are suitable for low power application only, not practical for high power application.
Further, among color LEDS, blue color LEDs are most popularly used for the advantage in lowest manufacturing cost. A packaging material containing a fluorescent substance can be used to change the color of the light of a blue LED into white color. However, this design has the drawbacks of high labor cost, low yield rate, and short LED working life.